Calamity Mod Wiki
PolterghastPhase 1
AI TypePolterghast AI
Damage150 / 240 / 264 / 280 (Contact)
120 / 192 / 212 / 224 (Blue Phantom Shot)
140 / 240 / 264 / 280 (Blue Phantom Blast)
Max Life350,000 / 560,000 /
KB Resist100%
Inflicts debuffMoon BiteMoon Bite
100% chance
Debuff duration15 seconds (Contact)
Debuff tooltipYou are unable to absorb healing effects
Inflicts debuffNightwitherNightwither
100% chance
Debuff duration2 seconds (Blue Phantom Shot and Blast)
Debuff tooltipIncinerated by lunar rays
Immune toConfusedPearl AuraNightwitherWhispering Death
Polterghast map.png
Map Icon
NecroghastPhase 2
AI TypePolterghast AI
Damage180 / 288 / 316 / 336 (Contact)
130 / 212 / 236 / 248 (Red Phantom Shot)
150 / 260 / 288 / 304 (Red Phantom Blast)
Max Life175,000 / 350,000
364,000 / 560,000
537,600 / 672,000
604,800 / 672,000
KB Resist100%
Inflicts debuffMoon BiteMoon Bite
100% chance
Debuff duration15 seconds (Contact)
Debuff tooltipYou are unable to absorb healing effects
Inflicts debuffWhispering DeathWhispering Death
100% chance
Debuff duration2 seconds (Red Phantom Shot and Blast)
Debuff tooltipDeath approaches; defense, attack power, and life regen reduced
Immune toConfusedPearl AuraNightwitherWhispering Death
NecroplasmPhase 3
AI TypePolterghast AI
Damage210 / 336 / 369 / 392 (Contact)
Max Life70,000 / 350,000
196,000 / 560,000
336,000 / 672,000
403,200 / 672,000
KB Resist100%
Inflicts debuffMoon BiteMoon Bite
100% chance
Debuff duration15 seconds (Contact)
Debuff tooltipYou are unable to absorb healing effects
Immune toConfusedPearl AuraNightwitherWhispering Death
Coins60 Gold Coin
Necroplasm map.png
Map Icon

Polterghast is usually the seventh Post-Moon Lord boss that you will face in your playthrough. Polterghast is summoned by using the Necroplasmic Beacon in the Dungeon at any time. Additionally, if Polterghast is not yet defeated in a world, it will spawn naturally after killing 30 Phantom Spirits.

This guide will mention items exclusive to Expert and Revengeance Mode with no special formatting and will follow the intended progression.

Terrain Preparation[]

A large, spacious area in the Dungeon should be cleared out with plenty of room to move. The arena should not have any places where you can get stuck; the floor and walls should be flat. Zen Potions help immensely while building the arena by preventing enemy spawns.

An alternative to a large arena is the "donut" arena, which is a 60x60 space surrounded by blocks with a 20x20 square in the center. Because Polterghast moves faster and deals more damage proportional to the amount of active tiles around it, this arena ensures that Polterghast receives no movement or damage bonuses, while still giving the player a good amount of space to dodge its attacks. If one is struggling with one arena style, it may be worth it to try another.

You can use Dungeon Walls Unsafe purchased from the Clothier in order to expand your dungeon or to create an artificial one elsewhere.

Gearing Up[]


Tarragon armor is the preferred choice for all classes; however, Lunar armors can still be effective if the player is adept with Polterghast's behavior.


  • Tarragon Wings (with Angel Treads) or Seraph Tracers are the preferred wings.
  • The Elysian Aegis or the Statis' Ninja Belt allow the player to make sharp turns and are very useful.
    • The Elysian Aegis additionally gives knockback immunity and many defensive boosts.
    • Statis' Ninja Belt additionally provides the chance of a ninja dodge and increased jump acceleration.
  • The Absorber is important for survivability by increasing damage reduction as well as giving increased jump acceleration.
  • The Community is a great all around accessory that boosts offensive and defensive stats as well as boosting flight time.
  • The Heart of the Elements provides many all-around boosts including damage, damage reduction, life regen, and jump acceleration.
  • The Astral Arcanum is a great option giving a chance to nullify projectile damage.
  • Melee players should use the Bloody Worm Scarf for its strong melee boosts as well as increased damage reduction.
  • Ranged players should use the Sniper Scope and Artemis Emblem, which both help in boosting damage output.
    • The Artemis Emblem additionally gives some life regen and ammo conservation.
  • Magic players should use the Sigil of Calamitas for its strong magic boosts.
  • Summoners can boost their minion count and damage with the Star-Tainted Generator and Statis' Curse.
  • The Dark God's Sheath can be a good accessory for Rogue players, provided they can gain stealth to perform stealth strikes.
    • It also provides several passive Rogue bonuses.


The weapons made from Uelibloom Bars or Bloodstone Cores are typically the best options for the fight.


  • The True Tyrant's Ultisword's high DPS should make the fight fairly straight-forward for Melee users, as the short range is mitigated by Polterghast generally staying close to the player.
  • The Seeking Scorcher is a good option if you would rather focus on dodging, since it can home into enemies and has a decent range.
  • The Mirror Blade is another option with good DPS provided that you have good aim.
  • The Aquatic Dissolution is a strong option that deals high damage to the boss if you can aim it.
  • The Mutilator, Holy Collider, and Stellar Striker are risky options that deal great damage at the cost of losing lots of health.
    • The Tarragon Cloak's effect of halving enemy contact damage greatly reduces the risk of using these weapons.
    • The Galactus Blade is a great sword that can decimate the boss, while letting the player stay further away from the boss.



  • The Sanguine Flare and Mistlestorm are excellent choices that deal high damage to Polterghast.
  • Viscera is a lower DPS option, but it greatly increases survivability with its healing.
  • The Elemental Ray is a decent choice, dealing good damage to Polterghast.
  • The Ultra Liquidator is an excellent secondary weapon for applying Ichor for long periods of time.
  • The Divine Retribution can decimate Polterghast, and the projectiles shot also home and go through walls.



  • The Cosmic Kunai is a strong option that deals excellent damage although it can be a bit risky.
  • Molten Amputators are another option that deal great DPS if Polterghast is lead through the boomerangs.
  • The Shattered Sun is a great option with its homing.
  • The Elemental Disk works well at close range during Phase 1, although it lacks in later phases.


  • The Well Fed buff provides a useful all around stat boost.
  • Farm Blood Orbs to easily craft many helpful potions that will increase your survivability.
  • Yharim's Stimulants can work well, providing a good stat boost. Note that they stack with their components.

The Fight[]

Polterghast will spawn off-screen, meaning you should be prepared to dodge the Polterghast as it approaches you. Polterghast has 3 phases.

Phase 1 should be largely treated like Plantera. Slowly circle Polterghast and watch out for the hooks and bouncing projectiles.

At 75% / 90% health, Polterghast transforms into Necroghast (Phase 2). The hooks no longer deal contact damage, but instead they occasionally shoot at you. Necroghast's projectiles are now red, faster, and deal more damage. Continue circling the boss in this phase.

At 33% / 50% / 60% health, Necroghast transforms into Necroplasm (Phase 3). It is highly recommended to use a weapon that inflicts Ichor in this phase such as Everglade Spray or the Golden Gun. At the start of this phase, Necroplasm immediately summons a clone. While this clone is alive, Necroplasm's damage reduction is increased by 30%, drastically reducing the damage it takes. Additionally, Phantoms begin to revolve around the player. At set intervals, they release Spirit orbs that can deal a lot of damage. It is important to keep an eye on when they shoot, so as to not get caught off guard. Unlike prior phases, circling is much less effective in this phase. Walking away slowly tends to work the best although very wide circles can work as well. Occasionally, the clone will make very fast lunges toward the player. Necroplasm can also do this. It is important to always keep moving and be ready to teleport with the Rod of Discord or Normality Relocator. When reaching 20% / 33% health, Necroplasm begins to occasionally summon Happy Phantom Spirits. Up to 3 can be summoned at a time. As long as you keep moving, they typically do not pose too much of a threat. Utilizing their Banner can minimize the threat they pose.

Be careful not to enter the Surface as it will cause Polterghast to enrage. When enraged, Polterghast gains a massive boost in speed, damage, projectile speed and fire rate, and damage reduction.

General Tips[]

  • The Normality Relocator is a very strong tool as it allows instantaneous teleportation.
    • Be wary while teleporting, as the player will fall at a much greater pace due to the Normality Relocator's effects.
  • In Death Mode, Polterghast will gain velocity and acceleration, gain increased max hook distance, and hook faster and more often as its HP decreases, which can pose a problem to less experienced players.
  • Heart Statues, Mana Statues and Heart Lanterns can be useful.